Inguinal canal and Spermatic cord pdf - Abdomen

Basic Anatomy

ward to the superficial inguinal nodes (see Fig. 4.19).

the axilla; below the level of the iliac crests, it drains down

axillary group of nodes, palpated on the posterior wall of

level of the iliac crests is drained upward to the posterior

(Fig. 4.19). The lymph of the skin of the back above the

downward and laterally to the superficial inguinal nodes

muscle. Below the level of the umbilicus, the lymph drains

pated just beneath the lower border of the pectoralis major

rior axillary (pectoral) group of nodes, which can be pal

wall above the level of the umbilicus is upward to the ante

The lymph drainage of the skin of the anterior abdominal

Superficial Lymph Vessels

Lymph Drainage of the Anterior Abdominal Wall

127

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inguinal node) caused by an infection or malignant tumor of

group of lymph nodes is clinically important. For example, it is

Skin and its Regional Lymph Nodes

Knowledge of the areas of the skin that drain into a particular

possible to find a swelling in the groin (enlarged superficial

the skin of the lower part of the anterior abdominal wall or that

of the buttock.

C L I N I C A L N O T E S

Deep Lymph Vessels

part of the posterior wall, namely, the deep inguinal ring.

therefore strongest where it lies opposite the weakest

inguinal ligament (see Figs. 4.3 and 4.8). This wall is

laterally by the origin of the internal oblique from the

External oblique aponeurosis, reinforced

Anterior wall.

Walls of the Inguinal Canal

external spermatic fascia.

give attachment to the

crura,

4.3, 4.5, and 4.8). The margins of the ring, sometimes called

immediately above and medial to the pubic tubercle (see Figs.

in the aponeurosis of the external oblique muscle and lies

is a triangular-shaped defect

superficial inguinal ring

The

the internal covering of the round ligament of the uterus).

(or

internal spermatic fascia

ring give attachment to the

upward from the external iliac vessels. The margins of the

it medially are the inferior epigastric vessels, which pass

and the symphysis pubis (see Figs. 4.4 and 4.8). Related to

ligament midway between the anterior superior iliac spine

transversalis, lies about 0.5 in. (1.3 cm) above the inguinal

* an oval opening in the fascia

deep inguinal ring,

The

Later, as the result of growth, the deep ring moves laterally.

ficial ring so that the canal is considerably shorter at this age.

child, the deep ring lies almost directly posterior to the super

immediately above the inguinal ligament. In the newborn

oblique muscle (see Figs. 4.3 and 4.8). It lies parallel to and

ficial inguinal ring, a hole in the aponeurosis of the external

versalis (see page 137), downward and medially to the super

extends from the deep inguinal ring, a hole in the fascia trans

The canal is about 1.5 in. (4 cm) long in the adult and

from the uterus to the labium majus.

females, it allows the round ligament of the uterus to pass

structures to pass to and from the testis to the abdomen. In

part of the anterior abdominal wall. In the males, it allows

The inguinal canal is an oblique passage through the lower

and para-aortic (lumbar) nodes.

the internal thoracic, external iliac, posterior mediastinal,

The deep lymph vessels follow the arteries and drain into

Inguinal Canal

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the

caput medusae

anterior axillary lymph nodes

superficial inguinal nodes

posterior axillary lymph nodes

FIGURE 4.19

Lymph drainage of the skin of the anterior and posterior abdominal walls. Also shown is an example of caput

medusae in a case of portal obstruction caused by cirrhosis of the liver.

openings for the fingers when the glove is viewed from the outside.

with the openings for the fingers seen inside a glove with the absence of

edges of the rings cannot be observed externally. Compare this arrangement

fascia is attached to the margins of the superficial inguinal ring so that the

attached to the margins of the deep inguinal ring and the external spermatic

rings as openings. One must remember that the internal spermatic fascia is

*A common frustration for medical students is the inability to observe these

128

CHAPTeR 4

to lessen this weakness.

interesting to consider how the design of this canal attempts

inal wall is a site of potential weakness in both sexes. It is

The inguinal canal in the lower part of the anterior abdom

Mechanics of the Inguinal Canal

the labium majus.

sage of the round ligament of the uterus from the uterus to

scrotum.) In the female, the smaller canal permits the pas

the abdominal cavity to enter a cooler environment in the

(Normal spermatogenesis takes place only if the testis leaves

to pass to and from the testis to the abdomen in the male.

The inguinal canal allows structures of the spermatic cord

Function of the Inguinal Canal

(see Fig. 4.7).

nal ligament and, at its medial end, the lacunar ligament

Upturned lower edge of the ingui

Floor or inferior wall.

oblique and transversus abdominis muscles (see Fig. 4.7).

Arching lowest fibers of the internal

Roof or superior wall.

anterior wall, namely, the superficial inguinal ring.

strongest where it lies opposite the weakest part of the

salis laterally (see Figs. 4.4 and 4.8). This wall is therefore

Conjoint tendon medially, fascia transver

Posterior wall.

The Abdomen: Part I—The Abdominal Wall

Except in the newborn infant, the canal is an oblique

and deep rings, lying some distance apart.

passage with the weakest areas, namely, the superficial

The anterior wall of the canal is reinforced by the fibers

the deep ring.

of the internal oblique muscle immediately in front of

The posterior wall of the canal is reinforced by the strong

conjoint tendon immediately behind the superficial ring.

On coughing and straining, as in micturition, defeca

canal is virtually closed (Fig. 4.20).

the contents of the canal against the floor so that the

ered toward the floor. The roof may actually compress

contract, flattening out the arched roof so that it is low

internal oblique and transversus abdominis muscles

tion, and parturition, the arching lowest fibers of the

When great straining efforts may be necessary, as in def

into the inferior vena cava on the right side.

wall and drains into the left renal vein on the left side and

vein is formed. This runs up on the posterior abdominal

about the level of the deep inguinal ring, a single testicular

the plexus ascends, it becomes reduced in size so that at

leaves the posterior border of the testis (see Fig. 4.21). As

pampiniform plexus,

An extensive venous plexus, the

Testicular Veins

(see Fig. 4.21).

the inguinal canal and supplies the testis and the epididymis

and descends on the posterior abdominal wall. It traverses

lumbar vertebra), the testicular artery is long and slender

A branch of the abdominal aorta (at the level of the 2nd

Testicular Artery

transports spermatozoa from the epididymis to the urethra.

part of the scrotum. It is a thick-walled muscular duct that

that can be palpated between finger and thumb in the upper

The vas deferens is a cordlike structure (see Figs. 4.5 and 4.21)

Vas Deferens (Ductus Deferens)

plies the cremaster muscle

Genital branch of the genitofemoral nerve, which sup

Remains of the processus vaginalis

Autonomic nerves

Testicular lymph vessels

Testicular veins (pampiniform plexus)

Testicular artery

Vas deferens

The structures are as follows:

Structures of the Spermatic Cord

inferior epigastric artery and ends at the testis.

(Fig. 4.21). It begins at the deep inguinal ring lateral to the

pass through the inguinal canal to and from the testis

The spermatic cord is a collection of structures that

the thighs (see Fig. 4.20).

lower part of the anterior abdominal wall is protected by

against the anterior abdominal wall. By this means, the

and the anterior surfaces of the thighs are brought up

assume the squatting position; the hip joints are flexed,

ecation and parturition, the person naturally tends to

Spermatic Cord

■

transversus

internal oblique

spermatic cord

conjoint
tendon

superficial
inguinal
ring

conjoint
tendon

FIGURE 4.20

Action of the muscles on the inguinal canal.

contract. Note also that the anterior surface of the thigh

Note that the canal is “obliterated” when the muscles

protects the inguinal region when one assumes the squat-

ting position.

Basic Anatomy

superficial inguinal ring

oblique aponeurosis and attached to the margins of the

derived from the external

External spermatic fascia

the abdominal wall (Fig. 4.23).

vaginalis descends into the scrotum through the layers of

abdominal wall. Each covering is acquired as the processus

tric layers of fascia derived from the layers of the anterior

The coverings of the spermatic cord are three concen

Fasciae)

Coverings of the Spermatic Cord (the Spermatic

(see page 222).

This nerve supplies the cremaster muscle (see Fig. 4.21)

Genital Branch of the Genitofemoral Nerve

the cord (see below).

The remains of the processus vaginalis are present within

Processus Vaginalis

nerves accompany the efferent sympathetic fibers.

the renal or aortic sympathetic plexuses. Afferent sensory

Sympathetic fibers run with the testicular artery from

the aorta at the level of the 1st lumbar vertebra (Fig. 4.22).

reach the lumbar (para-aortic) lymph nodes on the side of

canal and pass up over the posterior abdominal wall to

The testicular lymph vessels ascend through the inguinal

Lymph Vessels

129

Autonomic Nerves

■

pampiniform plexus

vas deferens

artery of vas

posterior

head

body

tail

epididymis

testis

lymph vessels

testicular artery

genitofemoral nerve

lymph vessels

artery of vas

pampiniform plexus

internal spermatic fascia

cremasteric fascia

vas deferens

external spermatic fascia

efferent ductules

skin of scrotum

epididymis

dartos muscle

membranous layer of

superficial fascia

(Colles' fascia)

external

spermatic fascia

cremasteric fascia

internal spermatic fascia

tunica vaginalis

vas deferens

mediastinum testis

seminiferous tubules

tunica albuginea

testicular artery

sinus of epididymis

FIGURE 4.21

Testis and epididymis, spermatic cord, and scrotum. Also shown are the testis and epididymis cut across in

horizontal section.

130

CHAPTeR 4

(see Figs. 4.4 and 4.5). It is in this

external spermatic fascia

inguinal ring and acquires a third tubular fascial coat, the

the external oblique, it evaginates this to form the superficial

from this abdominal layer. On reaching the aponeurosis of

abdominis muscle and therefore does not acquire a covering

vaginalis passes under the arching fibers of the transversus

(see Fig. 4.4). The processus

cremasteric fascia

known as the

are embedded in fascia, and thus the second tubular sheath is

The muscle fibers

cremaster muscle.

fibers, which form the

internal oblique muscle, it takes with it some of its lowest

(see Fig. 4.4). As it passes through the lower part of the

internal spermatic fas

and acquires a tubular covering, the

It traverses the fascia transversalis at the deep inguinal ring

as it does so, acquires a tubular covering from each layer.

layers of the lower part of the anterior abdominal wall and,

(see Fig. 4.23). The processus vaginalis passes through the

is formed

processus vaginalis

toneal diverticulum called the

of origin high on the posterior abdominal wall (L1), a peri

Before the descent of the testis and the ovary from their site

Development of the Inguinal Canal

must first consider the development of the inguinal canal.

To understand the coverings of the spermatic cord, one

salis and attached to the margins of the deep inguinal ring

derived from the fascia transver

Internal spermatic fascia

muscle

derived from the internal oblique

Cremasteric fascia

The Abdomen: Part I—The Abdominal Wall

■

cia

manner that the

d in both sexes. (In

inguinal canal is forme

inguinal canal during the seventh and eighth months of fetal

In the male, the testis descends through the pelvis and

(see Fig. 4.23).

gubernaculum

canal to the labioscrotal swelling, has condensed to form

lower pole of the developing gonad through the inguinal

Meanwhile, a band of mesenchyme, extending from the

the covering of the round ligament of the uterus.)

the female, the term spermatic fascia should be replaced by

the

life. The normal stimulus for the descent of the testis is testos

in the female, the only structures that pass through the

Thus,

round ligament of the uterus.

majus persists as the

lum extending from the uterus into the developing labium

the gonad descends no farther. That part of the gubernacu

becomes attached to the side of the developing uterus, and

ing the gubernaculum (see Fig. 4.23). The gubernaculum

In the female, the ovary descends into the pelvis follow

cia, the cremasteric fascia, and the internal spermatic fascia.

by three concentric layers of fascia: the external spermatic fas

down the inguinal canal. Thus, the spermatic cord is covered

vaginalis, they acquire the same three coverings as they pass

so on, follow the course previously taken by the processus

Because the testis and its accompanying vessels, ducts, and

in the developing scrotum by the end of the eighth month.

nerves, and lymph vessels. The testis takes up its final position

the processus vaginalis and pulls down its duct, blood vessels,

the posterior abdominal wall. The testis then passes behind

the gubernaculum and descends behind the peritoneum on

terone, which is secreted by the fetal testes. The testis follows

aorta

lumbar lymph nodes

superficial inguinal
lymph nodes

scrotal skin

testis

transpyloric
plane

FIGURE 4.22

Lymph drainage of the testis and the skin of

the scrotum.

testis

processus
vaginalis

gubernaculum

ovary

gubernaculum

tunica
vaginalis

testis

remains of
gubernaculum

remains of
processus
vaginalis

round ligament
of uterus

round
ligament
of ovary

FIGURE 4.23

Origin, development, and fate of the processus

into the scrotum and the descent of the ovary into the pelvis.

vaginalis in the two sexes. Note the descent of the testis

Basic Anatomy

ent motor nerve fibers travel in the genital branch of

of the genitofemoral nerve (L1 and 2), and the effer

ent fibers of this reflex arc travel in the femoral branch

The affer

cremasteric reflex.

the thigh. This is called the

to contract by stroking the skin on the medial aspect of

nerve (see page 222). The cremaster muscle can be made

is supplied by the genital branch of the genitofemoral

from the fascia transversalis. The cremaster muscle

cle; and, finally, the internal spermatic fascia is derived

masteric fascia is derived from the internal oblique mus

the aponeurosis of the external oblique muscle; the cre

explained. The external spermatic fascia is derived from

anterior abdominal wall on each side, as previously

ficial fascia and are derived from the three layers of the

These three layers lie beneath the super

Spermatic fasciae.

and separates the testes from each other.

tribute to a median partition that crosses the scrotum

ischiopubic rami. Both layers of superficial fascia con

membrane (see Fig. 4.1). At the sides, it is attached to the

perineal body and the posterior edge of the perineal

wall (Scarpa’s fascia), and behind it is attached to the

with the membranous layer of the anterior abdominal

(often referred to as Colles’ fascia) is continuous in front

ing skin. The membranous layer of the superficial fascia

fibers and is responsible for the wrinkling of the overly

This is innervated by sympathetic nerve

dartos muscle.

fat is, however, replaced by smooth muscle called the

membranous layers of the anterior abdominal wall; the

This is continuous with the fatty and

Superficial fascia.

remain separate and form the labia majora.)

eral labioscrotal swellings. (In the female, the swellings

in the midline indicates the line of fusion of the two lat

mented and forms a single pouch. A slightly raised ridge

The skin of the scrotum is thin, wrinkled, and pig

Skin.

The wall of the scrotum has the following layers:

mides, and the lower ends of the spermatic cords (see Figs.

anterior abdominal wall. It contains the testes, the epididy

The scrotum is an outpouching of the lower part of the

Scrotum

Scrotum, Testis, and Epididymides

the uterus to the superficial inguinal nodes.

vessels convey a small amount of lymph from the body of

ligament of the uterus and a few lymph vessels. The lymph

inguinal canal from the abdominal cavity are the round

131

4.4 and 4.21).

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the genitofemoral nerve. The function of the cremaster

cremaster muscles. It is now recognized that the testicular

be changed reflexly by the contraction of the dartos and

fully understood, but the surface area of the scrotal skin can

The control of testicular temperature in the scrotum is not

perature about 3°C lower than the abdominal temperature.

When they are located in the scrotum, they are at a tem

at a temperature lower than that of the abdominal cavity.

Normal spermatogenesis can occur only if the testes are

Fig. 4.21).

nect the rete testis to the upper end of the epididymis (see

con

efferent ductules

Small

rete testis.

channels called the

The tubules open into a network of

seminiferous tubules.

Lying within each lobule are one to three coiled

lobules.

of fibrous septa that divide the interior of the organ into

Extending from the inner surface of the capsule is a series

tunica albuginea.

fibrous capsule, the

level than the right. Each testis is surrounded by a tough

(see Figs. 4.5 and 4.21). The left testis usually lies at a lower

is a firm, mobile organ lying within the scrotum

testis

The

Testis

drains into the superficial inguinal lymph nodes (see Fig. 4.22).

Lymph from the skin and fascia, including the tunica vaginalis,

Lymph Drainage of the Scrotum

testis.

nalis is thus a closed sac, invaginated from behind by the

the processus and the peritoneal cavity. The tunica vagi

before birth, it becomes shut off from the upper part of

expanded part of the processus vaginalis; normally, just

medial, and lateral surfaces of each testis. It is the lower

within the spermatic fasciae and covers the anterior,

(see Figs. 4.4, 4.5, and 4.21). This lies

Tunica vaginalis

temperature and fertility, see below.

warmth and for protection against injury. For testicular

muscle is to raise the testis and the scrotum upward for

veins in the spermatic cord that form the pampiniform
plexus—together with the branches of the testicular
arteries, which lie close to the veins—probably assist in sta

stances to the seminal fluid to nourish the maturing sperm.

tion of fluid. Another function may be the addition of sub

mature. A main function of the epididymis is the absorp

storage space for the spermatozoa and allows them to

The long length of the duct of the epididymis provides

enters the spermatic cord.

which

vas deferens,

from the tail of the epididymis as the

long, embedded in connective tissue. The tube emerges

The epididymis is a much coiled tube nearly 20 ft (6 m)

(see Fig. 4.21).

sinus of the epididymis

the inner visceral layer of the tunica vaginalis and is called

between the testis and the epididymis, which is lined with

inferiorly. Laterally, a distinct groove lies

and a pointed

body,

head,

Fig. 4.21). It has an expanded upper end, the

testis, with the vas deferens lying on its medial side (see

is a firm structure lying posterior to the

epididymis

The

blood ascending to the abdomen within the veins.

arriving in the artery from the abdomen loses heat to the

heat exchange mechanism. By this means, the hot blood

bilizing the temperature of the testes by a countercurrent

Epididymis

tail

the

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Vasectomy

postoperative ejaculations, but that is simply an emptying process.

between ligatures. Spermatozoa may be present in the first few

upper part of the scrotal wall, and the vas deferens is divided

infertility. Under local anesthesia, a small incision is made in the

Bilateral vasectomy is a simple operation performed to produce

Now only the secretions of the seminal vesicles and prostate con-

stitute the seminal fluid, which can be ejaculated as before.

C L I N I C A L N O T E S